Exercise Keeps You Cancer Free

Modern miracle drugs like tamoxifen and raloxifene routinely cut risk for breast cancer in women whose medical histories or genes make them especially vulnerable to it.

But reams of research also suggest that exercise—an activity as old as the human race—substantially reduces the odds of ever getting the disease, lengthens survival and considerably enhances quality of life for women with breast cancer.

Scientists don't completely understand why exercise is so important, but they're actively looking for answers. Roughly two thirds of all breast cancers are considered estrogen-positive; that means that the hormone estrogen fuels their growth. The rest are estrogen-negative. Many experts believe regular exercise lowers the amount of estrogen circulating through the body in the bloodstream. So for certain types of breast cancer, less estrogen equals less fuel. Exercise also pares off hormonally active fat tissue. Fat manufactures a substance called aromatase that converts hormones known as androgens to estrogen. After menopause, when the ovaries stop cranking out high levels of estrogen, this hormonal cascade becomes the major source of estrogen in a woman's body.

Recently two large, carefully designed studies suggested exercise may work through more than just hormonal mechanisms linked to estrogen. In a study published last month in the Archives of Internal Medicine, researchers speculated that exercise might affect tumor aggressiveness. The researchers found that long-term moderate or strenuous activity over a lifetime cut risk for developing estrogen-negative invasive breast cancers (though not estrogen-positive cancers). Since fewer therapies are effective against estrogen-negative cancers, that's heartening news. Some earlier research on exercise suggests it lowers risk for estrogen-positive cancers, too. Scientists are also looking beyond estrogen at the effects exercise has on insulin, leptin and certain growth factors.

Read the complete article:

http://www.msnbc.msn.com/id/17887457/site/newsweek/

www.RobinThompson.com